borgo I'm in the UK and as far as I'm aware Starling Bank supports GrapheneOS. Each time it's has been broken and reported, their devs have responded saying they have been made aware of the issues and pushing a fix for GrapheneOS soon - and the fix comes about and sanity is restored.
There's even a (or multiple?) thread in this forum about it and in the GitHub repo dedicated to which banking apps work on G-OS.
I think just for that itself, these people deserve to be applauded and I've got myself and many of my folks (I've installed G-OS for as many as I could convince in my family and also among friends/colleagues) as I could to use Starling, even if they for some reason don't want it to be their main banking app. I see it similar to donating for a FOSS project or crowdfunding exercise. On top of that Starling is actually damn good banking experience.
So we should have a pin-up of all these banks (along with the country/ies they operate in) and encourage folks to give them a try. That way they have more customer base, feel it important to continue supporting G-OS and have our loyalty. That might also have an effect on other banks falling in line when they see a precedent (otherwise the banking software industry works with pre-historic constraints and herd mentality).